package Example9;

import java.text.DecimalFormat;
import java.util.Scanner;

public class Main3 {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        int N=scanner.nextInt();
        double sum=0;
        for (int i = 1; i <= N; i++) {
            sum+=i*1.000/N;
        }
        DecimalFormat df=new DecimalFormat("0.0000");
        System.out.println(df.format(sum));
    }
}
